I think the only time Mira's every been truly exhausted was at the end of our 11-day road trip last summer. Vising four different places, traveling through five different states, lots of field work and long offlead walks/runs every day, living in a house with many strange dogs and people she didn't really remember, mini-road trips most days to new places...and then returning to the new place we were staying. And then capping it off with a weekend of agility at a new place in near-100 degree temperatures. It was that long continuous drain for a week and a half with a lot of physical and mental work. Despite that, she still Q'd and placed 2nd in Masters for her last agility run of the weekend. But both of us were just "off" and I think we both slept a full day after coming home. Or would have, if Da Cookie-Baby had let us But no I've never worn her out to the point that she isn't up and ready to go the instant she thinks I might be doing something interesting. Which isn't to say she hasn't been tired...even very tired...but her personality is such that she will ignore being tired to work. The only way to tell is that the work may be slightly less snappy, or she will flop down faster when on break. Kim and Web it's harder to tell. Even after 13+ miles of hiking with a pack, Kim still has zoomies (though she will also sleep deeply). Kim gets bored with long exercise and will feign exhaustion but if you unclip the leash she'll tear around like a bat out of hell and be chasing squirrels and grinning up a storm. And Webster is this strange sort of guy where he doesn't *need* a ton of exercise...his demands are more mental as in, if he doesn't get something to think about he will either make up something I don't like or he will start to get tense about everything...but he can go forever at a moderate pace with little/no sign of fatigue. I guess really it just depends what you mean by exhausted. Too tired to do more? What sort of recovery period is allowed. If ten minutes later they are ready to go again, does that count as having been (briefly) exhausted? They all have different tolerances for that sort of thing.